1. Field of the Invention
The present invention relates to a structure of seat cushion frame in a vehicle seat, such as an automotive seat.
2. Description of Prior Art
Ordinarily, in descending from a vehicle seat or particularly from an automotive seat, a passenger will put his or her thigh or buttocks on one lateral bolster portion of a seat cushion of the seat which faces towards the door of automobile. Thus, a weight of the passenger is exerted on that seat cushion bolster portion. Considering this passenger's behavior and weight load, there has been known a reinforced structure of seat cushion frame as shown in FIG. 1.
FIGS. 1 to 3 illustrate this conventional seat cushion frame structure.
With particular reference to FIG. 2, it is observed by the imaginary line that a passenger (M) is about to descend from a seat, putting his or her thigh on one lateral bolster section (SC1') of seat cushion (SC') to apply most of his or her weight thereto.
FIG. 1 shows the conventional seat cushion frame (F) of a pan type having a standing side frame (11) fixed on the left-side lateral frame section (F1) and a reinforcement side frame (10) provided fast on the right-side lateral frame section (F2). The reinforcement side frame (10) is to face towards the door of automobile (DS) when assembling it with a seat upholstery into a cabin of the automobile (not shown).
The seat cushion (SC') is formed by upholstering the seat cushion frame (F) with a foam cushion member (C') and a covering member (S') as shown in FIG. 3.
In the FIG. 3, designation (SC1') denotes a lateral bolster portion of the seat cushion (SC') disposed at the side of door of automobile (DS), where the weight of passenger (M) is frequently applied as mentioned above. The reinforcement side frame (10) is provided beneath such lateral bolster portion (SC1') in order to (i) receive the thigh or buttocks of passenger (M) with a stable supporting touch, (ii) avoid extreme lowering of that particular bolster portion (SC1') and (iii) resist a great load from the passenger's weight.
The reinforcement side frame (10) is welded at one lateral edge thereof to the upper surface of right-side frame section (F2) of seat cushion frame (F), extending generally along the whole length-wise direction of seat cushion frame (F) and projecting upwardly therefrom to the same level with that of the left side frame (11).
In this connection, as can be seen from FIG. 2, it has been noticed that what is mostly pressed by the passenger's thigh or buttocks is the rearward upper area of the door-side bolster portion (SC1'). Hence, according to this conventional seat cushion (SC'), it would be preferred to make relatively thick that rearward upper area of bolster portion (SC1') as indicated by (C1') in FIG. 3. However, this would increase the height of the door-side bolster portion (SC1'), resulting in a hindrance against the descending or climbing action of the passenger from or onto the seat cushion (SC') because there would be a more frequent contact between the bolster portion (SC1') and the passenger's legs or buttocks. On the contrary, even if the layer portion (C1') of cushion member (C') is made smaller in thickness, the upper wall (10a) of reinforcement side frame (10) will be felt hard unpleasantly by the passenger, which deteriorates the advantages of reinforcement side frame (10) for allowing the passenger to smoothly descend from or climb onto the seat with a comfortable touch.